Compresto vs ImageOptim: Choosing the Right Compression Tool for Mac

If you're comparing Compresto and ImageOptim for your Mac compression needs, the decision comes down to scope. ImageOptim is a focused, free tool that excels at lossless image optimization. Compresto is a broader solution that handles videos, images, and PDFs in one application with more control over output settings.

At-a-Glance Comparison

Both tools help Mac users reduce file sizes, but they target different use cases:

Feature	Compresto	ImageOptim
Image Compression	Yes — lossy and lossless options	Yes — primarily lossless optimization
Video Compression	Yes — MP4, MOV, and more	No
PDF Compression	Yes	No
Compression Control	Quality presets, target size (video only)	Automatic optimization only
Batch Processing	Yes	Yes
Hardware Acceleration	Apple Silicon optimized	No
Price	Paid with free trial	Free and open-source
File Size Targeting	Video only	Not available

Understanding ImageOptim

ImageOptim has earned a loyal following among web developers and designers. It removes unnecessary metadata and applies lossless compression to make images smaller without visible quality loss.

What ImageOptim does well:

• Lossless optimization — Strips EXIF data, color profiles, and embedded thumbnails
• Format-specific tools — Uses MozJPEG, PNGCrush, Zopfli, and other specialized compressors
• Drag-and-drop workflow — Drop images and they're optimized automatically
• Free and open-source — No cost, no subscriptions
• CLI integration — Automate compression in build scripts

For web developers optimizing assets before deployment, ImageOptim is a solid choice. Drop your exported images onto the window, and they get smaller while looking identical.

Where ImageOptim falls short:

• No target size control — You can't specify "make this image exactly 200 KB"
• Images only — Videos and PDFs require separate tools
• Limited quality settings — Less control over compression aggressiveness
• No hardware acceleration — Doesn't leverage Apple Silicon

Understanding Compresto

Compresto approaches compression as a workflow problem. Rather than optimizing one file type, it consolidates video, image, and PDF compression into a single Mac-native application.

What Compresto does well:

• Multi-format support — Videos (MP4, MOV), images (PNG, JPEG, GIF, SVG, TIFF), and PDFs
• Target file size for videos — Specify exactly how small you need video output
• Quality presets — Balance between quality and size without manual tuning
• Hardware acceleration — Fast processing on Apple Silicon Macs
• Menu bar access — Quick compression without launching a full window

For users who regularly share files across messaging apps, email, or social media, handling everything in one tool saves context-switching time.

Compression Approaches Compared

The philosophical difference between these tools matters for your workflow.

ImageOptim: Automatic and Lossless

ImageOptim aims to make files smaller without any visible quality loss. It runs multiple optimization passes using specialized algorithms for each format:

• JPEG — MozJPEG for recompression
• PNG — PNGCrush, Zopfli, AdvPNG
• GIF — Gifsicle for frame optimization
• SVG — SVGO for code cleanup

The results are modest but safe. A 500 KB PNG might become 400 KB—the image looks identical, just with less overhead.

Compresto: Controlled and Flexible

Compresto gives you control over the output. You can choose between:

• Quality presets — Low, Medium, High compression levels
• Target file size (videos) — Specify exactly how large the video output should be
• Format options — Maintain format or convert during compression

Quality presets let you decide how aggressively to compress images and PDFs. The trade-off is some quality loss at aggressive settings—but you're in control of that decision.

ImageOptim asks: "How can I make this smaller without changing it?" Compresto asks: "How much compression do you want?" These are different questions with different answers.

Real-World Scenario Comparisons

Scenario 1: Optimizing Website Assets

You have 50 product photos to prepare for an e-commerce site.

ImageOptim approach:

1. Export images from your editor
2. Drag all 50 images onto ImageOptim
3. Wait for automatic optimization
4. Use the optimized files

Result: ~15-25% size reduction with zero quality loss. Fast and simple.

Compresto approach:

1. Import images into Compresto
2. Choose a quality preset based on your size requirements
3. Batch compress all files
4. Use the compressed files

Result: Variable reduction depending on settings chosen. More control, potentially smaller files with quality trade-offs you accept.

Winner: For lossless web optimization, ImageOptim. For meeting strict file size budgets, Compresto.

Scenario 2: Sharing Screenshots in Slack

You need to share a bug report screenshot. Slack has file size considerations, and smaller uploads load faster for team members.

ImageOptim approach:

1. Take screenshot (2.3 MB PNG)
2. Drop on ImageOptim (now 1.9 MB)
3. Upload to Slack

The reduction helps, but the file is still fairly large.

Compresto approach:

1. Take screenshot (2.3 MB PNG)
2. Use Medium or High compression preset
3. Get a much smaller file (400-600 KB)
4. Upload to Slack

Winner: Compresto delivers more significant size reductions for sharing scenarios.

Scenario 3: Compressing Files for Email

You need to send a project update with a video walkthrough, three screenshots, and a PDF document.

ImageOptim approach:

1. Compress images with ImageOptim
2. Find a separate tool for the video
3. Find another tool for the PDF
4. Attach everything to email

Three tools for one task.

Compresto approach:

1. Add all files to Compresto
2. Batch compress everything
3. Attach to email

Winner: Compresto handles the entire workflow without switching apps.

Quality and Output Comparison

Let's look at how each tool handles the same source file:

PNG Screenshot (3.2 MB original, 2560x1440)

Tool	Output Size	Quality Loss	Time
ImageOptim	2.6 MB	None (lossless)	8 sec
Compresto (Low compression)	2.1 MB	Minimal	3 sec
Compresto (Medium)	800 KB	Some visible	2 sec
Compresto (High compression)	400 KB	Noticeable on zoom	2 sec

JPEG Photo (4.1 MB original, 4000x3000)

Tool	Output Size	Quality Loss	Time
ImageOptim	3.4 MB	None	12 sec
Compresto (Low compression)	2.8 MB	Minimal	4 sec
Compresto (Medium)	1.2 MB	Slight	3 sec
Compresto (High compression)	600 KB	Visible	3 sec

ImageOptim consistently produces slightly larger files because it refuses to degrade quality. Compresto gives you options across the size-quality spectrum.

The Broader Picture: All-in-One vs Specialized

ImageOptim does one thing very well. It's a sharp tool for a specific job.

Compresto does several things competently. It's a Swiss Army knife for compression tasks.

If you already have solutions for video compression (like HandBrake) and PDF compression (like Preview's export), ImageOptim fills the remaining gap nicely—and costs nothing.

If you'd rather not juggle multiple tools, Compresto consolidates the workflow. One app, one interface, all your compression needs.

When to Choose Each Tool

Choose ImageOptim when:

• Lossless is required — You can't accept any quality reduction
• Budget is zero — Free software is a hard requirement
• Images only — You don't need video or PDF compression
• Build automation — You need CLI tools for scripts and pipelines
• Web development workflow — Optimizing assets before deployment

Choose Compresto when:

• Aggressive compression needed — Quality presets let you shrink files significantly
• Multi-format needs — Working with videos, images, and PDFs together
• Sharing workflow — Preparing files for Discord, email, Slack, etc.
• Mac-native preference — You value Apple Silicon optimization and menu bar access
• Time efficiency — One tool for all compression tasks

Can You Use Both?

Yes—and some workflows benefit from it.

For example: Use Compresto for aggressive compression when sharing files, and use ImageOptim to squeeze every last byte from web assets where lossless matters.

The tools don't conflict. They solve different problems.

Final Verdict

ImageOptim is the right choice if you specifically need lossless image optimization and prefer free, open-source tools. It does its job well without asking for payment.

Compresto is the right choice if you need flexible compression across multiple file types with control over output size. The paid license gets you a unified workflow and hardware-accelerated performance.

Neither tool is universally "better"—they're built for different needs. Match the tool to your workflow, not the other way around.

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Need to compress videos, images, and PDFs in one place? Compresto handles all three with Mac-native performance and flexible quality controls.